A: Mn shows exceptional M.P. in 3d series
R: Its outer configuration is `4s^(2) 3d^(5)`

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To solve the question, we need to evaluate the assertion and reason provided:

**Assertion (A):** Mn shows exceptional melting point in the 3d series.
**Reason (R):** Its outer configuration is \(4s^2 3d^5\).

### Step 1: Analyze the Assertion
- Manganese (Mn) is known to have an exceptional melting point compared to other transition metals in the 3d series.
- The melting point of a metal is influenced by the strength of metallic bonds, which depend on the number of delocalized electrons available for bonding.

### Step 2: Understand the Electronic Configuration
- The electronic configuration of Mn is \(4s^2 3d^5\).
- The \(3d^5\) configuration indicates that the 3d subshell is half-filled, which is a particularly stable arrangement due to symmetry and exchange energy.

### Step 3: Relate the Configuration to Melting Point
- A half-filled \(3d\) subshell means that the electrons are more tightly bound to the nucleus and less delocalized.
- This tight binding leads to stronger metallic bonds, which in turn results in a higher melting point.

### Step 4: Evaluate the Reason
- The reason states that the outer configuration \(4s^2 3d^5\) is the cause of the exceptional melting point.
- Since the half-filled configuration contributes to the stability and strength of metallic bonds, this reason is indeed a correct explanation for the assertion.

### Conclusion
- Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is:

**Option 1:** Both assertion and reason are true, and the reason is the correct explanation of the assertion.

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